JP5808649B2 - Electronic material cleaner - Google Patents

Description

The present invention relates to a cleaning agent for electronic materials and a method for producing electronic materials.
More specifically, the present invention relates to a cleaning agent suitable for removing abrasive grains after polishing of the surface and polishing debris in the manufacture of an electronic material, and a method for manufacturing an electronic material using the cleaning liquid.

Electronic materials, especially magnetic disks, are becoming smaller and higher capacity year by year, and the flying height of magnetic heads is becoming smaller. For this reason, there is a demand for a substrate in which abrasive grains, polishing scraps, and the like do not remain in the manufacturing process of the magnetic disk substrate. There is also a demand for reduction of surface roughness, minute waviness, and surface defects such as scratches and pits.

The magnetic disk manufacturing process includes a substrate process (1), which is a process for producing a flattened substrate, and a media process (2), which is a process for sputtering a magnetic layer on the substrate.
Of these, in the substrate step (1), polishing with a slurry containing abrasive grains is performed to flatten the substrate, and then particles such as the slurry and generated polishing scraps are rinsed and washed, and further removed by rinsing. The missing particles are cleaned and removed completely in a subsequent cleaning process.
By the way, with the recent increase in recording density of magnetic disks, studies using two or more stages of polishing processes have been made. That is, polishing is performed mainly for the purpose of removing relatively large waviness, large pits and other surface defects on the substrate surface in the first stage polishing, and fine scratches and pits are removed by the second stage polishing. While adopting a method of forming a very flat surface.

If the abrasive grains and polishing debris used in the polishing process remain on the surface of the substrate obtained by the first stage polishing, it causes scratches during the second stage polishing process, and has an adverse effect. Most of them are removed in the second stage polishing process, but what remains without being removed becomes a defect. Even in the second stage polishing, if these foreign substances remain after the polishing, they become defects in the subsequent media process, which adversely affects the quality.
In order to solve these problems, it is necessary to remove abrasive grains and polishing debris at the end of the polishing process carried out in each stage. Agents are becoming necessary.

On the other hand, in the media step (2), a step of polishing the substrate surface again may be performed in order to remove foreign substances adhering during transportation or storage and to sputter a magnetic layer uniformly on the substrate. Also in this polishing process, there is a problem of adhesion of cutting scraps and abrasive particles in the slurry, and a high-performance cleaning agent is required.

Conventionally, for these purposes, a method for improving the particle removability by using a surfactant has been proposed.
For example, an anionic polymer surfactant such as polyacrylate is used to improve the removal of alumina (Patent Document 1), an anionic surfactant such as dialkylsulfosuccinate and a glycol ether are used. A method (Patent Document 2) for improving the removability of diamond has been proposed.

However, in the above-described cleaning agents of Patent Documents 1 and 2, the present situation is that the removal of abrasive grains and polishing debris after the polishing process has not been able to cope with the higher recording density in recent years. In order to achieve a high recording density of the magnetic disk, a high detergency for abrasive grains that are difficult to remove is required.
By the way, when using a cleaning agent containing a surfactant and having a redox potential within a specific range as a cleaning agent for a flat panel display substrate or a photomask substrate, the inventors cut a mother glass. It has been found that the performance of dispersing generated glass chips (cutting waste) is excellent (Patent Document 3).
However, although this technology is excellent for removing glass cutting waste for flat panel display substrates, it is less effective for cleaning that removes abrasive grains, so a magnetic disk substrate whose main purpose is to remove abrasive grains It cannot be applied to cleaning agents.

JP 11-43791 A Japanese Patent Laid-Open No. 2002-212597 JP 2010-163608 A

However, the level required for cleaning in recent years has become more severe, and the cleaning agents for magnetic disk substrates of Patent Documents 1 and 2 have become insufficient.
As a result of analysis of the contents of dirt by the inventors, it was found that a very small amount of surfactant remains on the surface of the substrate after cleaning. That is, after rinsing with the cleaning liquid, when the rinsing is insufficient due to a short rinsing time, components in the cleaning liquid may remain on the substrate surface. In addition, many abrasive grains may remain on the substrate for the same reason.
Although the detailed mechanism is unknown, the surfactant in the cleaning liquid is physically adsorbed on the substrate during the cleaning, and a part of the surfactant remains on the substrate surface with a small amount of rinsing. Thereafter, during the cleaning process, the abrasive grains are physically adsorbed to the surfactant remaining after being physically adsorbed on the substrate. As a result, it is considered that the cleaning performance for the abrasive grains is also adversely affected.
By the way, the use of a surfactant having a relatively low surface tension improves the affinity of the cleaning agent for organic substances and the wettability to the substrate, and as a result, the cleaning property may be improved. Residues, even in trace amounts, change the wettability of the substrate surface, causing serious adverse effects such as non-uniformity in sputtering of magnetic films and the occurrence of stripes and spots, making it difficult to achieve high recording density To.

Therefore, the cleaning performance for abrasive grains is very high, and there is very little residue on the substrate surface of organic substances such as surfactants that have an adverse effect. Another object of the present invention is to provide a cleaning agent for electronic materials that exhibits high cleaning performance and a method for producing the electronic materials.

As a result of investigations to achieve the above-mentioned object, the present inventors have obtained a high detergency for abrasive grains by using a specific type of reducing agent, and further obtained a surfactant having a relatively low surface tension. It was found that the residue of the cleaning agent component on the substrate can be extremely reduced by limiting the content to a specific concentration or less. As a result, the inventors have found that the adverse effect on the uniformity of sputtering of the magnetic film due to the wettability due to the residual surfactant can be avoided, and the present invention has been achieved.
That is, the present invention includes a surfactant (B) having a reductone (A) as a reducing agent and water as essential components and having a surface tension at 25 ° C. of 50 mN / m or less when diluted to 1% by weight. Is a cleaning agent for electronic materials having a content of less than 0.01% by weight.

The cleaning material for electronic materials and the method for producing electronic materials according to the present invention are particularly problematic in the manufacturing process of magnetic disk substrates (particularly glass substrates for magnetic disks and aluminum substrates for magnetic disks plated with Ni-P). Excellent cleanability for abrasive grains. Further, even when the rinsing time is short, there is little residue on the substrate.
For this reason, it is possible to provide an electronic material having a high cleanliness required for increasing the recording density, for example, required for uniformly sputtering the magnetic film.

  The cleaning agent for electronic materials of the present invention contains 0.01 to 10% by weight of reductone (A) having reducibility and water, and the surface tension at 25 ° C. when diluted to 1% by weight is 50 mN / m. It is a cleaning agent for electronic materials whose content of the following surfactant (B) is less than 0.01% by weight.

In the present invention, the electronic material is not particularly limited, and includes a magnetic disk substrate (glass substrate, aluminum substrate and aluminum substrate with Ni-P plating), semiconductor substrate (semiconductor element, silicon wafer, etc.), compound Examples include semiconductor substrates (SiC substrates, GaAs substrates, GaN substrates, AlGaAs substrates, etc.), sapphire substrates (LEDs, etc.), optical lenses, printed wiring boards, optical communication cables, micro electromechanical systems (MEMS), and crystal resonators. In view of cleaning properties, a magnetic disk substrate or the like is preferable.
In particular, the electronic material cleaning agent of the present invention is useful as a cleaning agent for glass substrates and aluminum substrates for magnetic disks.

  The reductone (A) having reducibility, which is an essential component of the electronic material cleaning agent of the present invention, may be a compound having a ketoenediol group represented by the following general formula (1) in the molecule.

L-ascorbic acid, isoascorbic acid, ester ring-opening compounds of L-ascorbic acid; these esters (L-ascorbic acid sulfate, L-ascorbic acid phosphate, L-ascorbyl palmitate, L-ascorbic acid Tetraisopalmitic acid ester, L-ascorbic acid isopalmitic acid ester, isoascorbic acid phosphoric acid ester, isoascorbic acid palmitic acid ester, isoascorbic acid tetraisopalmitic acid ester); salts thereof (for example, sodium salt, potassium salt, Amine salts and the like).
Of these, preferred are L-ascorbic acid and a salt of L-ascorbic acid.

  Of these, L-ascorbic acid, isoascorbic acid; and salts thereof are preferred from the viewpoint of abrasive cleaning properties and availability, and L-ascorbic acid and salts thereof are more preferred. (A) may be used independently and may use 2 or more types together.

Moreover, as a salt of reductone, the sodium salt of L-ascorbic acid may be mix | blended from the beginning, and L-ascorbic acid in a system and sodium hydroxide may form a salt in a washing | cleaning liquid.

The content of reductones (A) in the electronic material cleaning agent of the present invention is 0.01 to 10% by weight, preferably 0.1 to 5% by weight.
Further, the electronic material cleaning agent of the present invention may be further diluted with water when used, and the content of the reductone (A) at the time of use is 0.001 to 5% by weight, which is detergency. From the viewpoint, it is preferably 0.01 to 1% by weight.

Examples of water that is another essential component of the electronic material cleaning agent of the present invention include ultrapure water, ion-exchanged water, RO water, and distilled water. Ultrapure water is preferable from the viewpoint of cleanliness.

When the surfactant (B) having a surface tension of 50 mN / m or less is contained in an amount of 0.01% by weight or more, it is difficult to remove with a running water rinse and may remain on the substrate. As a result, sputtering of the magnetic film is not uniform, which is not preferable.
The content of the surfactant (B) in the electronic material cleaning agent of the present invention is less than 0.01%, preferably less than 0.005%, more preferably less than 0.003%, but has an adverse effect. It is preferable that the surfactant is not contained as much as possible.

The surfactant (B) in the present invention is a surfactant having a surface tension of 50 mN / m or less at 25 ° C. when diluted to 1% by weight. The surface tension is measured using a platinum plate using a surface tension meter based on the Wilhelmy method.

Examples of the surfactant (B) in the present invention include those having a surface tension of a 1% by weight aqueous solution of 50 mN / m or less among ionic surfactants and nonionic surfactants.
Examples of the ionic surfactant include sodium dialkyl sulfosuccinate, soap, alpha olefin sulfonic acid, alkyl benzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl sulfate ester, alkyl ether sulfate ester, sulfosuccinic acid, sulfated oil, ether carboxylic acid, Among quaternary ammonium, imidazolinium betaine, amidopropyl betaine, alkylamine, alkylamide, etc., those having a surface tension of 1% by weight aqueous solution of 50 mN / m or less can be mentioned.

Nonionic surfactants include polyoxyalkylene alkyl ether, polyoxyalkylene glycol ether, polyoxyalkylene polyalkylaryl ether, fatty acid ester, alkylamine ethylene oxide adduct, alkylamide ethylene oxide adduct, alkylamine oxide and the like. 1% by weight aqueous solution having a surface tension of 50 mN / m or less.

  The electronic material cleaning agent of the present invention preferably further contains a chelating agent (C) in order to improve detergency.

Examples of the chelating agent (C) include aminopolycarboxylates {eg, ethylenediaminetetraacetate (EDTA), diethylenetriaminepentaacetate (DTPA)}, hydroxycarboxylates (eg, tartrate, citrate, gluconic acid) Salts), phosphonates {eg, 1-hydroxyethylidene-1, 1-diphosphonate (HEDP)}, condensed phosphates (eg, tripolyphosphate), and the like.
Of these, HEDP and DTPA are preferable from the viewpoint of detergency.

Content at the time of use of chelating agent (C) in the cleaning agent for electronic materials of this invention is 0.001 to 5 weight%, Preferably it is 0.01 to 0.5 weight% from a viewpoint of detergency. is there.

  The cleaning agent of the present invention may further contain an acid and an alkali in addition to the reducing reductones (A), water, surfactant (B) and chelating agent (C).

Examples of the acid include inorganic acids such as sulfamic acid and organic acids such as phytic acid. Examples of the alkali include inorganic alkalis such as sodium hydroxide and amines such as diethanolamine.
The pH during use of the electronic material cleaning agent of the present invention is 1 to 12, and is preferably 3 to 10, particularly preferably 4 to 8, from the viewpoint of liquid stability.

Another embodiment of the present invention is a method for producing an electronic material including a step of washing the electronic material after the polishing step using the electronic material cleaning agent, and is particularly suitable for a method for producing a magnetic disk substrate. ing.
However, the present invention is not limited to a magnetic disk substrate, and is widely useful in the manufacture of electronic materials as long as it is the manufacture of electronic materials that require the removal of abrasive slurry and polishing debris.

  When the cleaning agent for electronic materials of the present invention is used for the production of a magnetic disk substrate, it can be used after the first stage polishing in the substrate process, after the second stage polishing, or in the media process.

An example of the manufacturing process (part of the substrate process) of the magnetic disk substrate using the cleaning agent of the present invention will be described below by taking a glass substrate for hard disk as an example.
(1) After wrapping the glass substrate, rinse with running water to create the glass substrate.
(2) The substrate is set in a polishing apparatus, and the substrate is polished with a polishing slurry containing cerium oxide.
(3) The substrate after polishing is rinsed with running water, taken out of the polishing apparatus, dipped or scrubbed using the cleaning agent of the present invention, and rinsed again with running water.
(4) Then, after scrub cleaning using the cleaning agent of the present invention, rinse with running water again.
(5) The substrate is set again in the polishing apparatus, and the substrate is polished with a polishing slurry containing colloidal silica.
(6) The substrate after polishing is rinsed with ultrapure water and rinsed, and then the substrate is removed from the polishing apparatus, dip or scrubbed using the cleaning agent of the present invention, and rinsed again with running water.

  In the case of an aluminum substrate for hard disk, alumina is generally used instead of cerium oxide in the step (2).

Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

[Production Example 1]
In a 1 liter stainless steel autoclave equipped with a stirrer and a temperature controller, 10 parts of a 25% aqueous solution of 200 parts (1.1 mole parts) of lauryl alcohol and tetramethylammonium hydroxide (hereinafter abbreviated as TMAH) (0 .027 mol parts) and dehydrated at 100 ° C. under reduced pressure of 4 kPa or less for 30 minutes. 430 parts (9.8 mole parts) of EO was added dropwise over 3 hours while controlling the reaction temperature at 100 ° C., and then aged at 100 ° C. for 3 hours to obtain a crude product. This crude product was maintained at 150 ° C. for 2 hours under a reduced pressure of 2.6 kPa or less to decompose and remove the remaining TMAH, and lauryl which is a nonionic surfactant for the blending of Comparative Examples 3 and 5 630 parts of 9 mol of alcohol EO adduct was obtained.

[Production Example 2]
In a 1 liter stainless steel autoclave equipped with a stirrer and a temperature controller, 185 parts (1.0 mole part) of laurylamine and 3.6 parts (0.01 mole part) of 25% TMAH aqueous solution were charged at 100 ° C., It dehydrated under reduced pressure of 4 kPa or less for 30 minutes. 264 parts (6.0 mol parts) of EO was added dropwise over 3 hours while controlling the reaction temperature at 100 ° C., and then aged at 100 ° C. for 3 hours to obtain a crude product. This crude product was held at 150 ° C. under a reduced pressure of 2.6 kPa or less for 2 hours to decompose and remove the remaining TMAH to obtain 445 parts of a laurylamine EO 6 mol adduct as a nonionic surfactant.

[Production Example 3]
A reaction vessel capable of temperature control and stirring was charged with 300 parts of isopropyl alcohol and 100 parts of ultrapure water, and the reaction vessel was purged with nitrogen, and then heated to 75 ° C. While stirring at 30 rpm, 407 parts of a 75% aqueous solution of acrylic acid and 95 parts of a 15% isopropyl alcohol solution of dimethyl 2,2′-azobisisobutyrate were simultaneously added dropwise over 3.5 hours.
After completion of the dropwise addition, the mixture was stirred at 75 ° C. for 5 hours, and then ultrapure water was intermittently added so that the system did not solidify, and the mixture of water and isopropyl alcohol was distilled off until isopropyl alcohol could not be detected. The obtained polyacrylic acid aqueous solution was neutralized with 450 parts of DBU until the pH became 7.0, and dried under reduced pressure to obtain a polyacrylic acid DBU salt.

[Production Example 4]
100 parts of ethylene dichloride was charged into a reaction vessel equipped with a stirrer capable of temperature control and refluxing, and after purging with nitrogen under stirring, the temperature was raised to 90 ° C. to reflux ethylene dichloride. 120 parts of styrene and an initiator solution prepared by previously dissolving 1.7 parts of 2,2′-azobisisobutyronitrile in 20 parts of ethylene dichloride are separately added dropwise to the reaction vessel separately over 6 hours. Polymerization was carried out for another hour after completion. After the polymerization, the mixture was cooled to 20 ° C. under a nitrogen seal, 105 parts of anhydrous sulfuric acid was added dropwise over 10 hours while controlling the temperature at 20 ° C., and a sulfonation reaction was further carried out for 3 hours after the completion of the addition. After the reaction, the solvent was distilled off and solidified, and then 345 parts of ultrapure water was added and dissolved to obtain a polystyrenesulfonic acid aqueous solution. The obtained polystyrene sulfonic acid aqueous solution was neutralized with 25% TMAH aqueous solution (about 400 parts) until the pH became 7, and dried to obtain polystyrene sulfonic acid TMAH salt as an anionic surfactant.

The following compounds in Table 1 were used as follows. As other compounds, commercially available reagents were used.
Polycarboxylic acid sodium salt: “Caribbon L-400” manufactured by Sanyo Chemical Industries
Dialkylsulfosuccinic acid sodium salt: “Sanmorin OT-70” manufactured by Sanyo Chemical Industries

Examples 1-11 and Comparative Examples 1-7
Each component was blended so as to have the composition shown in Table 1, and stirred at 25 ° C. with a magnetic stirrer at 40 rpm for 20 minutes to obtain the cleaning agent of the present invention and the cleaning agent for comparison.
The cleaning agent was further diluted 50 times with ultrapure water to prepare a sample solution for performance test.

Various performance evaluation tests with different types of abrasives for cleaning properties of the cleaning agent and persistence on the substrate and different substrate materials were performed by the following methods.
This evaluation was conducted in a clean room of class 1,000 (FED-STD-209D, US Federal Standard, 1988) to prevent contamination from the atmosphere.

<Detergency test-1>
Using a commercially available colloidal silica slurry (“COMPOL 80” particle size of about 80 nm, manufactured by Fujimi Incorporated) as an abrasive, a 3.5-inch Ni—P plated aluminum substrate for a magnetic disk was polished under the following conditions.
Polishing equipment: “NFD-4BL” manufactured by Nano Factor
Slurry supply speed: 50 mL / min Load: 30 g weight / cm ²
Rotation speed: surface plate 30rpm, gear 20rpm
Polishing time: 5 minutes

After polishing the substrate, a contaminated substrate was prepared by rinsing the surface with ultrapure water for 1 minute with running water and blowing with nitrogen.
The prepared contaminated substrate was immersed in a 1 L glass beaker containing 1,000 parts of each of the sample liquids prepared above, and washed with an ultrasonic cleaner (200 kHz) at 30 ° C. for 5 minutes. After cleaning, the substrate was taken out, rinsed again with ultrapure water for 1 minute, and then blown with nitrogen gas and dried to obtain an evaluation substrate. The surface of the aluminum substrate was observed with a surface inspection device (“Micro-Max VMX-7100” manufactured by Vision Cytec Co., Ltd.), and the number of adhered particles was counted using image analysis software “Sigmascan”.

In addition, although it is necessary to sufficiently rinse (for example, 5 minutes or more) in a normal detergency test, the cleaning agent of the present invention is required to have a high degree of detergency in recent years. Strict conditions were used to determine whether particle removal was sufficient.
Moreover, it tested similarly with the ultrapure water as a blank instead of the washing | cleaning liquid. At that time, the number of adhered particles of the blank was 850.
The detergency test was determined according to the following criteria, and the determination results are shown in Table 1.

[Judgment criteria for detergency test]
5: Number of adhered particles is less than 1/100 of blank 4: Number of adhered particles is 1/100 to 1/20 of blank
3: The number of adhered particles is 1/20 to 1/5 of the blank.
2: Number of particles attached is 1/5 to 1/2 of blank
1: Number of particles adhering to half or more of blank

<Detergency test-2>
Evaluation was carried out by the same operation and judgment criteria as in Detergency Test-1, except that a commercially available alumina slurry (“WA # 20000” manufactured by Fujimi Incorporated, particle size of about 0.4 μm) was used instead of colloidal silica. The number of blank particles attached was 350.

<Detergency test-3>
Evaluation was performed by the same operation and judgment criteria as in the detergency test-1, except that a commercially available diamond slurry (“1/10 PCS-WB2” manufactured by Nano Factor, particle size of about 100 nm) was used instead of colloidal silica. The number of blank particles attached was 420.

<Detergency test-4>
The same operation and criteria as in Detergency Test-1 except that a commercially available glass substrate for 2.5-inch magnetic disk was used instead of the 3.5-inch Ni-P plated aluminum substrate for magnetic disk. It was evaluated with. The number of blank particles attached was 650.

<Detergency test-5>
Evaluation was made using the same operation and judgment criteria as in Detergency Test-4 except that a commercially available ceria slurry (“CES-303” manufactured by AGC Seimi Chemical Co., Ltd., particle size of about 0.4 μm) was used instead of the commercially available colloidal silica slurry. did. The number of blank particles attached was 450.

<Detergency test-6>
Evaluation was carried out using the same operation and judgment criteria as in Detergency Test-4 except that a commercially available diamond slurry (“1/10 PCS-WB2” manufactured by Nano Factor, particle size of about 100 nm) was used instead of the commercially available colloidal silica slurry. . The number of blank particles attached was 550.

<Residual prevention test-1>
The aluminum substrate was immersed in a performance test sample solution at 30 ° C. for 5 minutes, rinsed with running ultrapure water for 1 minute, and then dried by blowing a nitrogen stream.
The surface of the aluminum substrate after drying was observed with a differential interference microscope (manufactured by Nikon, OPTIPHOT-2, magnification 400 times), and the residual prevention property was determined according to the following criteria.
When the substrate on which the cleaning agent remains is observed with a microscope, the remaining portion appears as a striped pattern. Therefore, the residual prevention property can be evaluated by the presence or absence of the stripe pattern.
Moreover, it tested similarly with the ultrapure water as a blank. In that case, no stripes appear on the blank.
The results are shown in Table 1.

[Judgment criteria for residual prevention test]
○: Equivalent to blank, no residue stripes
×: Stripe pattern of residue is clearly seen compared to blank

<Residual prevention test-2>
Except for carrying out with the glass substrate in place of the aluminum substrate, evaluation and judgment were made by the same operation and judgment criteria as in the residual prevention test-1.

From Table 1, the cleaning liquids of Examples 1 to 11 containing reductones having reducibility and having a surfactant concentration of less than a certain concentration have less residual abrasive grains adhering to the aluminum substrate and the glass substrate, and the cleaning performance. Is high. Further, it can be seen that even when the rinse time is short, the residue of the cleaning liquid on the aluminum substrate and the glass substrate is high.
On the other hand, the cleaning agent of Comparative Example 1 using only reductones having no reducing property is the same as the blank in cleaning properties with respect to abrasive grains. The cleaning agents of Comparative Examples 2 and 3 containing reductones having a reducing property and a surfactant at a certain concentration or more have a slightly improved cleaning performance with respect to abrasive grains, but are not at a residual level that satisfies the increase in capacity, and the substrate Therefore, there is a possibility that the yield in magnetic film sputtering is significantly reduced.
Moreover, the cleaning agent of the conventional comparative example 4 which consists only of sodium polyacrylate whose surface tension is 50 mN / m or more has a bad cleaning property with respect to an abrasive grain. The conventional cleaning agent of Comparative Example 5 containing sodium dialkylsulfosuccinate is poor in both cleaning performance with respect to abrasive grains and persistence with respect to the substrate.
The cleaning agents of Comparative Examples 6 and 7 containing a surfactant having a surface tension of 50 mN / m or less in a certain concentration or more have poor cleaning properties with respect to abrasive grains and residual properties with respect to the substrate.

The cleaning agent for electronic materials of the present invention can greatly improve the cleaning properties for abrasive grains compared to conventional cleaning agents. In addition, there is very little persistence to the substrate. Therefore, it can be used as a cleaning agent for a magnetic disk substrate such as a hard disk whose recording density is increasing. In addition, the method for producing an electronic material of the present invention can be used for a magnetic disk substrate such as a hard disk that requires a particularly high cleaning level for the remaining abrasive grains.

Claims (5)

Reductone having reducibility (A) 0.01 to 10% by weight, water and chelating agent (C), and when diluted to 1% by weight, the surface tension at 25 ° C. is 50 mN / m or less. A cleaning agent for electronic materials, wherein the content of the surfactant (B) is less than 0.01% by weight , wherein the chelating agent (C) is diethylenetriaminepentaacetic acid salt .   The cleaning agent for electronic materials according to claim 1, wherein the reductones (A) are at least one member selected from the group consisting of L-ascorbic acid, isoascorbic acid and salts thereof. Electronic materials, electronic materials cleaning agent according to claim 1 or 2 is a magnetic disk substrate. The manufacturing method of an electronic material including the process of wash | cleaning an electronic material using the cleaning agent for electronic materials in any one of Claims 1-3 The method of manufacturing an electronic material according to claim 4 , wherein the electronic material is a magnetic disk substrate.